Functional MR imaging of the human cervical spinal cord.

BACKGROUND AND PURPOSE: Although research with functional MR imaging of the brain has proliferated over the past 5 years, technical limitations, such as motion, chemical shift, and susceptibility artifacts, have impeded such research in the human spinal cord. The purpose of this investigation was to determine whether a reliable functional MR imaging signal can be elicited from the cervical spinal cord during simple motor activity. METHODS: Subjects performed three different motor tasks that activate different segments of the spinal cord. Gradient-echo-planar imaging on a 1.5-T clinical unit was used to image cervical spinal cords of human subjects. Another group of subjects was imaged while performing isometric exercise to study the relationship between the blood oxygenation level-dependent (BOLD) signal and applied force. RESULTS: Task-dependent BOLD activity was detected in all subjects. Signal amplitude varied between 0.5% and 7%. Moreover, a linear relationship was found between the applied force and the signal amplitude during isometric exercise. While regions of activation were distributed throughout the spinal cord, concentrated activity was found in the anatomic locations of expected motor innervation. CONCLUSION: The functional MR imaging signal can be reliably detected with motor activity in the human cervical spinal cord on a 1.5-T clinical unit. The location of neural activation has an anatomic correspondence to the myotome in use. The strength of the BOLD signal is directly proportional to the level of muscular activity.

The relationship between the functional abilities of patients with cervical spinal cord injury and the severity of damage revealed by MR imaging.

BACKGROUND AND PURPOSE: The appearance of the damaged spinal cord after injury correlates with initial neurologic deficit, as determined by the American Spinal Injury Association grade and manual muscle test score, as well as with recovery, as assessed by manual muscle test scores. The purpose of this study was to determine whether the presence of spinal cord hemorrhage and the size and location of spinal cord edema on MR images is predictive of functional recovery in survivors of cervical spinal cord injury (SCI). METHODS: The degree of damage to the cervical spinal cord was measured on the MR images of 49 patients who underwent imaging within 72 hours of sustaining SCI. The effects of hemorrhage and length/location of edema on changes in the value of the motor scale of the functional independence measure (FIM) were assessed on admission to and discharge from rehabilitation. RESULTS: Patients without spinal cord hemorrhage had significant improvement in self-care and mobility scores compared with patients with hemorrhage. There was no significant effect of spinal cord hemorrhage on changes in locomotion and sphincter control scores. The rostral limit of edema positively correlated with admission and discharge self-care scores and with admission mobility and locomotion scores. Edema length had a negative correlation with all FIM scales at admission and discharge. CONCLUSION: The imaging characteristics of cervical SCI (hemorrhage and edema) are related to levels of physical recovery as determined by the FIM scale. Imaging factors that correlate with poor functional recovery are hemorrhage, long segments of edema, and high cervical locations.

Neurologic outcome of early versus late surgery for cervical spinal cord injury.

STUDY DESIGN: A prospective analysis evaluating neurologic outcome after early versus late surgery for cervical spinal cord trauma. OBJECTIVES: The study was conducted to determine whether neurologic and functional outcome is improved in traumatic cervical spinal cord-injured patients (C3-T1, American Spinal Injury Association grades A-D) who had early surgery (<72 hours after spinal cord injury) compared with those patients who had late surgery (>5 days after spinal cord injury). SUMMARY OF BACKGROUND DATA: There is considerable controversy as to the appropriate timing of surgical decompression and stabilization for cervical spinal cord trauma. There have been numerous retrospective studies, but no prospective studies, to determine whether neurologic outcome is best after early versus late surgical treatment for cervical spinal cord injury. METHODS: Patients meeting appropriate inclusion criteria were randomized to an early (<72 hours after spinal cord injury) or late (>5 days after spinal cord injury) surgical treatment protocol. The neurologic and functional outcomes were recorded from the acute hospital admission to the most recent follow-up. RESULTS: Comparison of the two groups showed no significant difference in length of acute postoperative intensive care stay, length of inpatient rehabilitation, or improvement in American Spinal Injury Association grade or motor score between early (mean, 1.8 days) versus late (mean, 16.8 days) surgery. CONCLUSIONS: The results of this study reveal no significant neurologic benefit when cervical spinal cord decompression after trauma is performed less than 72 hours after injury (mean, 1.8 days) as opposed to waiting longer than 5 days (mean, 16.8 days).

Use of shoulder flexors to achieve isometric elbow extension in C6 tetraplegic patients during weight shift.

The anterior deltoid muscle has been found to be active during elbow extension in normal volunteers and in C6 tetraplegic patients lacking a functional triceps. Using surface electromyography (EMG) on normal volunteers and on patients with spinal cord injury (SCI) at the C6 motor level, we evaluated whether the anterior deltoid and biceps brachii muscles are active during closed chain elbow extension in a simulated weight shift position. Thirteen normal volunteers performed isometric contractions at 5 submaximal levels of force ranging from 4-25 kg. Six SCI patients performed isometric contractions at force levels of 20%, 40%, 60%, 80% and 100% maximum voluntary contraction (MVC). Surface EMG over the right biceps, triceps, and anterior deltoid muscles was recorded for each participant and the root mean square (rms) electromyographic activity level for each muscle was determined at each level of force. Statistical analyses using repeated ANOVA with Tukey HSD post-hoc tests were performed for each level of force. The results indicated increasing rms activity of the triceps and anterior deltoid muscles with increasing force in normal volunteers to a significant degree (P < 0.05). SCI patients showed significant increasing activity of the anterior deltoid with increasing force, but showed minimal triceps rms activity. In both groups, the biceps showed minimal rms activity. SCI patients exhibited significantly greater rms activity of the anterior deltoid at low force compared with normal volunteers. The results suggest that the anterior deltoid aids in isometric elbow extension during a simulated weight shift maneuver.

Forecasting motor recovery after cervical spinal cord injury: value of MR imaging.

PURPOSE: To determine whether magnetic resonance (MR) imaging quantification of cervical spinal cord damage improves the prediction of motor recovery after spinal cord injury. MATERIALS AND METHODS: The extent of cervical spinal cord injury was measured on MR images obtained in 104 patients (aged 17-70 years) within 72 hours of spinal cord injury. The effects of hemorrhage and edema length on motor outcome were examined for at least 12 months. RESULTS: Patients with spinal cord hemorrhage had significantly lower upper and lower extremity motor scores at the time of injury and at 12 months than did patients without hemorrhage (P < .001). There was little recovery of lower extremity function even in patients without hemorrhage. Upper extremity motor function improved significantly in all patients (P < .001); patients without hemorrhage showed the largest improvements. The motor recovery rates for patients without hemorrhage were 0.74 (upper extremities; range, 0-1) and 0.55 (lower extremities; range, 0-1); those for patients with hemorrhage were 0.31 (range, 0-1) and 0.091 (range, 0-1). Stepwise multiple regression analyses indicated that MR information on hemorrhage and the length of edema increases the ability to predict clinical outcome by 16%-33% over that with initial clinical scores alone. CONCLUSION: An initial MR imaging evaluation of the spinal cord after spinal cord injury provides supplemental prognostic information on the recovery of motor function in the upper and lower extremities.

Spinal cord injury and bladder recovery.

OBJECTIVE: To investigate whether spinothalamic tract preservation and posterior column sparing are predictors of neurogenic recovery of bladder function after spinal cord injury (SCI). DESIGNS AND PARTICIPANTS: In a retrospective review, the initial perianal pinprick sensation (S4.5 dermatomes) and position sense of the great toes were examined and correlated with bladder function at 1 year after SCI in 19 consecutive spinal cord injured patients (age 18 to 68 years), Frankel A-D, with spinal injury (level C-4-T-12). All patients were admitted to the Regional Spinal Cord Injury Center of Delaware Valley (RSCIDDV) within 72 hours of injury between July 1990 and June 1991 and were available for a 1-year follow-up evaluation. MAIN OUTCOME MEASURES: The correlation of initial perianal pinprick and great toe position sensation with bladder management approximately 1 year after SCI. RESULTS: During the initial 72 hours, 10 of the 19 patients had positive perianal pinprick sensation and 9 did not feel the pin. Eight patients had positive great toe position sense, and 11 had no proprioception. At the 1-year follow-up visit, 7 of the 10 patients with initial preserved perianal pinprick were voiding volitionally, whereas none of the 9 patients who did not have pinprick voided volitionally at 1-year after SCI. Six of the 8 with initial preserved great toe position sense were voiding volitionally at 1 year, but only 1 of the original 11 without initial toe position sense was voiding volitionally. CONCLUSIONS: Both perianal pinprick sensation and toe position sense are sensitive in predicting return of bladder function. Although both tests have positive predictive value, their negative predictive values are much more noteworthy. A patient without initial position sense of the great toes will likely not regain volitional voiding, whereas a patient without initial perianal pinprick sensation will definitely not regain volitional voiding.

Strength post-spinal cord injury: myometer vs manual muscle test.

This study was designed to compare changes in strength after spinal cord injury (SCI) with the use of a hand held myometer to the manual muscle test (MMT). Eighty-eight C4-C8 Frankel A-D tetraplegic subjects were tested at various times up to 2 years post-SCI. Elbow flexor strength on successive examinations were grouped according to their early and later MMT scores (3.5 with no change in MMT. 3.5 to 4.0, and 3.5 to 4.5; 4.0 with no change in MMT, 4.0 to 4.5, and 4.0 to 5.0; 4.5 with no change in MMT, and 4.5 to 5.0). For each group, later myometric measurements (MYO) were expressed as percents of their earlier MYO and were analyzed using paired Student t-tests. Later MYO were 116, 205, 232% (P > 0.05, P < 0.002, P < 0.05) of their earlier MYO for groups 3.5 with no change in the MMT, 3.5 to 4.0, and 3.5 to 4.5 respectively. Later MYO were 140, 139, 191% (P < 0.05, P < 0.02, P < 0.0001) of their earlier MYO for groups 4.0 with no change in MMT, 4.0 to 4.5, and 4.0 to 5.0 respectively. Later MYO were 127 and 126% (P < 0.01, P < 0.02) of their earlier MYO for groups 4.5 with no change in MMT and 4.5 to 5.0 respectively. In conclusion the hand held myometer detected changes in muscle strength not detected by the MMT.

Intrauterine onset of a mononeuropathy: peroneal neuropathy in a newborn with electromyographic findings at age one day compatible with prenatal onset.

Mononeuropathies are unusual at birth, and electromyographic (EMG) definition the first day of life has not been reported previously. Although neonatal mononeuropathies may be related to obstetric complications, prenatal mechanisms also merit consideration. We report an infant, born with a peroneal neuropathy, whose EMG was performed 18 h after birth. An isolated peroneal nerve lesion with lack of compound muscle action potential and the presence of fibrillation potentials, confined to the tibialis anterior muscle, suggested a primary intrauterine mechanism for this mononeuropathy. Because of an infant's small size, the temporal profile used in adults for appearance of EMG signs of wallerian degeneration may not apply. Inaccurate conclusions may result if the EMG standards for timing adult nerve injury are applied to newborns. To our knowledge, previous published cases of neonatal mononeuropathies have not included babies whose first EMG was performed before age 4 days. Therefore, an EMG study shortly after birth needed to be accomplished if strong support for the hypothesis of a prenatal onset were to be generated. Our findings are compatible with an intrauterine onset of this baby's peroneal neuropathy.

Future ambulation prognosis as predicted by somatosensory evoked potentials in motor complete and incomplete quadriplegia.

OBJECTIVE: The purpose of this prospective study was to determine the efficacy of tibial somatosensory evoked potentials (SEPs) in predicting ambulation in tetraplegic individuals. DESIGN: This was a prospective study of a cohort of cervical spinal cord-injured patients who had SEPs recorded within 72 hours to 2 weeks post-SCI and whose ambulation outcome was followed up to 2 years post-SCI. SETTING: Regional Spinal Cord Injury (SCI) Center. PATIENTS: All male and female subjects admitted to the center from 1988 to 1991 between the ages of 15 and 60 years who demonstrated C4 through T1 complete and incomplete acute SCIs were asked to participate in this study. MEASUREMENTS: The tibial nerve cortical SEPs were graded as either present or absent. The waveforms were also graded as less than 0.5 microV or > or = 0.5 microV. Quadriceps strength plus touch and pin sensation were tested within 72 hours to 2 weeks post-SCI. Ambulation was rated as absent, exercise, household, or community. The ambulatory and clinical status were assessed monthly for 3 months, and then at 6, 12, 18, and 24 months post-SCI. Statistical analysis using the two-tailed Fisher's exact test was performed relating the initial clinical and SEP data to ambulation outcome up to 24 months post-SCI. RESULTS: All 13 subjects with a right and/or left quadriceps manual muscle test (MMT) greater than 0/5 became ambulatory. Of the 9 subjects with an initial bilateral quadriceps MMT = 0/5, only 1 recovered enough lower limb function to ambulate (p = .0001). One of the 7 subjects with absent touch sensation in the lower limbs became ambulatory, whereas 14 of the 15 subjects with touch sensation present became ambulatory (p = .002). All 7 subjects with absent pin sensation in the lower limbs were nonambulatory, and 14 of 15 subjects with pin sensation present became ambulatory (p < .0001). Of the 9 subjects with bilaterally absent cortical SEP waveforms, 2 became ambulatory. Twelve of the 13 subjects with a cortical SEP wave present became ambulatory (p = .0015). Of the 10 subjects with a cortical SEP wave amplitude less than 0.5 microV, only two became ambulatory, whereas all 12 subjects with an amplitude > or = 0.5 microV became ambulatory (p = .00014). In no subject did the SEP predict future ambulation where the clinical examination did not also predict recovery of ambulation. CONCLUSION: Both the early postinjury clinical evaluation and the SEP predicted ambulation outcome to a significant degree, but the SEP offered no additional prognostic accuracy over that provided by the clinical examination.

Traumatic focal posterior tibialis muscle denervation.

The purpose of this case presentation is to demonstrate posterior tibialis muscle (PTM) denervation as a cause of traumatic plantarflexion inversion weakness. In a 42-year-old woman, severe pain, swelling, and ecchymosis over the medial aspect of her left ankle developed after she twisted it while playing tennis. Plantarflexion inversion weakness developed (grade 3/5). The strength of all other muscle groups of the lower extremity was normal. Her pin and light touch sensation were normal in the left lower extremity. Deep tendon reflexes were equal and active at both knees and ankles. A magnetic resonance image of the left leg, ankle, and foot performed 1 month after injury demonstrated an intact posterior tibialis tendon behind the medial malleolus and edema-like increased signal intensity in the PTM on the T1-weighted image consistent with denervation. On electromyographic testing, there were continuous fibrillation and positive sharp wave potentials in every site tested in the PTM without any voluntary motor unit activity. The left extensor hallucis, left gastrocnemius, and lumbar paraspinal muscles were normal. In conclusion, combined magnetic resonance imaging and electromyographic studies supported denervation of the PTM as the cause of plantarflexion inversion weakness, rather than posterior tibialis tendon rupture in this patient.

Elbow extension using anterior deltoids and upper pectorals in spinal cord-injured subjects.

OBJECTIVE: Surface electromyography was used to identify muscles active in isometric elbow extension in spinal cord-injured (SCI) patients. DESIGN: Tetraplegic subjects participated in this cohort study aimed at identifying some of the muscles that are active during isometric elbow extension. SETTING: Regional Spinal Cord Injury (SCI) Center. PATIENTS: The patients had to have a C6 motor level on the right side (wrist extensor > or = 3/5) with 0/5 or 1/5 elbow extensor muscle power. Of 32 patients who could be contacted by telephone, 6 eventually were able to make it to the SCI center for testing. MEASUREMENTS: The patients performed a series of isometric elbow extension contractions of 25%, 50%, and 75% of maximum voluntary contraction (MVC) as measured by a force transducer. Surface electromyography (EMG) of the right elbow extensor, anterior deltoid, and upper pectoral muscles was measured using the root mean square (rms) of the amplitude of the motor unit activity as the parameter of muscle activity. Statistical analyses were performed using a repeated analysis of variance (ANOVA) with Tukey post-hoc HSD for each percentage of MVC. RESULTS: For each muscle tested, there was significantly (p < 0.05) greater rms activity for each percentage of MVC except between 50% and 75% MVC of the elbow extensor muscle. However, the elbow extensor muscle had minimal EMG activity when compared with the amplitude of the rms activity of the anterior deltoid and upper pectoral muscles for each percentage of MVC. CONCLUSION: The results of the study suggest that the anterior deltoid and the upper pectoral muscles exert an isometric elbow extension force for C6 quadriplegic patients.

Neuromuscular disease: rehabilitation and electrodiagnosis. 1. Anatomy and physiology of nerve and muscle.

This article of the Self-Directed Physiatric Education Program to assist practitioners and trainees in physical medicine and rehabilitation identifies the anatomy and physiology of nerve, neuromuscular junction, and muscle as they relate to rehabilitation of diseases affecting these structures. Structural relationships of the spinal roots, peripheral nerves, motor units, and muscle fibers are outlined, with structural, functional, and electrodiagnostic correlations. Features of nerve and muscle biochemistry and physiology are reviewed as they relate to common neurological diseases, age, and sex. The spontaneous potentials, motor unit activities, and nerve conduction abnormalities found in diseases of nerve and muscle also are described.

Wrist strength measured by myometry as an indicator of functional independence.

The purpose of this study was to show that independence of self care activities of motor complete quadriplegic patients related better to the force of contraction of the wrist extensor (WE) muscles measured by a hand held myometer than to the manual muscle test (MMT) for grades 3 to 5. The patients (n = 24), identified by having unilaterally or bilaterally functional WE muscle (MMT > or = 3/5) with bilateral elbow extensor (EE) muscles < 3/5, were evaluated at 2 to 6 months after injury for four feeding activities utilizing the Quadriplegia Index of Function (QIF). We found 54% were independent drinking from a cup, 58% using a spoon or fork, 13% cutting food, and 23% pouring liquids. Comparisons were made between right, left, and bilateral mean myometry scores and median MMT scores for each of the QIF activities. The independent group of patients had myometry scores 54 to 140% greater (p < 0.05) than those patients dependent in the self care activity except when the right or left WE myometric score was analyzed for cutting food (p = 0.1). MMT comparisons showed no significant median score differences in any activity performed. There were no patients with only one WE muscle > or = 3/5 (n = 9) who were able to cut food or pour liquids independently. In conclusion, myometry appeared to be a better indicator than the MMT for some self care activities evaluated utilizing the Quadriplegia Index of Function.

Transcranial magnetic stimulation: cortical motor maps in acute spinal cord injury.

This investigation examined the motor pathways of four, C5-6 spinal cord injured (SCI) patients within 6-17 days of injury. Mapping of the motor cortex was achieved by transcranial magnetic stimulation (TMS) applied to the scalp. Motor evoked potentials were recorded from target muscle groups (Biceps brachii and Abductor pollicis brevis m.). Evidence of an expanded cortical map of the preserved contralateral biceps muscle was demonstrated in these patients as early as 6 days. These findings suggested that early motor re-organization may occur following acute cervical spinal cord injury in man.

Biceps vs extensor carpi radialis recovery in Frankel grades A and B in spinal cord injury patients.

Clinical literature suggests that the wrist extensors show a trend of achieving functional strength earlier than the biceps after spinal cord injury (SCI). Basic research, however, demonstrated that proximal muscles recover earlier than distal muscles after partial denervation. The purpose of this study was to compare biceps to extensor carpi radialis (ECR) recovery of muscle strength in 39 motor complete cervical SCI patients. Biceps (n = 19) and ECR (n = 20) with a 72 hour or 1 week motor grade of 1/5 were compared. Testing was performed weekly for 1 month, and again at 2, 3, 6 and 12 months post injury. The median recovery times to increase one motor grade were: biceps = 2 months and ECR = 2.5 months (p < 0.3). The median recovery times to increase two motor grades were: biceps = 2 months and ECR = 3 months (p < 0.4). In conclusion, there was no significant difference between the rates of recovery of the biceps and the ECR up to 12 months post SCI.